I've owned my 2009 Scion xB with the notorious oil-burning 2AZ-FE engine since January. Since that time I've driven it 7500 miles and have observed a moderate oil burn rate, so I planned to do a Berryman's soak at the next oil change. I did two full bottles at a 24 hour interval, then gave each cylinder a five second spray of fogging oil and (because it was pouring rain) let it set another 24 hours before installing a new set of Autolite double platinum spark plugs. One oddity I noticed while installing the plug in cylinder #2 was that I didn't feel the washer compress, it just bottomed out like you would expect from a plug that had been removed and reinstalled. I didn't think to look at the washer before installing it but the other three felt normal.
It took FOREVER to start! I was afraid I would overheat the starter so I took a break and hooked up my 10 amp charger (which pegged the needle) and waited a few minutes to try again. When it finally started it sputtered and rumbled like they usually do after a piston soak but smoothed out quite a bit. I let it run a few minutes and then proceeded with the oil change. All the normal dash indicators were lit up due to the misfires during startup.
After changing the oil I started it again to check for leaks and it was running much rougher, so much so that it was barely drivable and almost died going into drive. I pulled the codes and had cylinder 2 misfire and ignition circuit open codes. I removed the plug and inspected it but the only odd thing I saw was some carbon in the threads so I cleaned them off and reinstalled. I had a new Denso coil I had bought for the other xB so I went ahead and installed it and that immediately corrected the misfire. I'm not sure if the coil was actually bad or if the carbon (left in the threads from all the B12 that had been flung out of the dirty cylinder) had caused a faulty seal. Is that a thing? I figured the new coil was doing any good sitting in the box so I might as well swap it in in case it might matter.
Can moderately dirty spark plug threads cause enough of a compression leak to cause a misfire? Can just removing and reinstalling a coil kill it?
Also, a tip for people contemplating doing a piston soak: my experience now having done several of them is that an ounce of TCW-3 two stroke oil down the holes prior to starting is the best approach to reestablishing compression on a dry piston/cylinder. I won't use fogging oil again because it sure didn't seem to help much this time. When I used TCW-3 on two different engines they started noticeably faster than the times I didn't.
It took FOREVER to start! I was afraid I would overheat the starter so I took a break and hooked up my 10 amp charger (which pegged the needle) and waited a few minutes to try again. When it finally started it sputtered and rumbled like they usually do after a piston soak but smoothed out quite a bit. I let it run a few minutes and then proceeded with the oil change. All the normal dash indicators were lit up due to the misfires during startup.
After changing the oil I started it again to check for leaks and it was running much rougher, so much so that it was barely drivable and almost died going into drive. I pulled the codes and had cylinder 2 misfire and ignition circuit open codes. I removed the plug and inspected it but the only odd thing I saw was some carbon in the threads so I cleaned them off and reinstalled. I had a new Denso coil I had bought for the other xB so I went ahead and installed it and that immediately corrected the misfire. I'm not sure if the coil was actually bad or if the carbon (left in the threads from all the B12 that had been flung out of the dirty cylinder) had caused a faulty seal. Is that a thing? I figured the new coil was doing any good sitting in the box so I might as well swap it in in case it might matter.
Can moderately dirty spark plug threads cause enough of a compression leak to cause a misfire? Can just removing and reinstalling a coil kill it?
Also, a tip for people contemplating doing a piston soak: my experience now having done several of them is that an ounce of TCW-3 two stroke oil down the holes prior to starting is the best approach to reestablishing compression on a dry piston/cylinder. I won't use fogging oil again because it sure didn't seem to help much this time. When I used TCW-3 on two different engines they started noticeably faster than the times I didn't.
